The Universe and the Bucket

• Galileo and others, meaning the concept predates Einstein, realized that velocity was relative; motion in a straight line is undetectable without some comparison but changes in velocity can be felt
• Newton conducted an experiment in which he spun a bucket of water; the water did not move at first but then started to spin causing the water surface to become concave, however when the bucket slowed and stopped the water still spun and retained the concave shape
• He explained the results using absolute space, the water is in motion compared to absolute space, however absolute space is unobservable
• Newton argued that the behavior of the water in the bucket was scientific proof of absolute space
• Ernst Mach, in the 1800s, wondered if the room which held the bucket, or the earth or the stars might be the other side in the waters relative motion instead of absolute space
• He argued that in completely empty space there is no difference between spinning and not; in other words, without a reference there is no such thing as spinning
• Mach argued that the force felt from spinning is proportional to the amount of matter in the universe (my thought: is this a way of saying it’s related to gravity?)
• My thought:  What about dark matter?  We can’t see it but it is matter so would we feel spin without a visual reference?